Load equalizer



Nov. 26, 1968 e. w. WILKIE LOAD EQUALI Z ER Filed Oct. 7, 1966 FIG.

4 Sheets-Sheet. 1

INVENTOR. GEORGE W. WILKIE ATTORNEY Nov. 26, 1968 G. w. WILKIE 3,413,028

LOAD EQUALI ZER Filed Oct. 7. 1966 4 Sheets-Sheet 2 FIG.

INVENTOR. GEORGE W. WILKIE 'ATTORNEY G. W. WILKIE LOAD EQUALIZER Nov. 26, 1968 4 Sheets-Sheet 3 Filed Oct.

200m Oh INVENTOR. GEORGE W. WILKIE W44) ATTORNE Nov. 26, 1968 G. w. WILKIE 3,413,028

LOAD EQUALI Z ER Filed Oct. '7 1966 4 Sheets-Sheet 4 INVENTOR. GEORGE W. WILKIE ATTORNEY United States Patent Office 3,413,928 Patented Nov. 26, 1968 3,413,028 LOAD EQUALIZER George W. Wilkie, Wilmington, DeL, assignor to Sun Shipbuilding & Dry Dock Company, Chester, Pa., a corporation of Pennsylvania Filed Oct. 7, 1966, Ser. No. 585,080 7 Claims. (Cl. 294-67) ABSTRACT OF THE DISCLOSURE A rectangular frame is suspended at its four corners from a single-point suspension (cargo hook), and each of the four corners of the frame is coupled by means of a separate set of falls to a respective corner of the load (which may be a retangular spreader from which is suspended a container). All four of the sets of falls are operated simultaneously by powered driving means carried by the frame, thereby to adjust the transverse central plane of the frame with respect to the transverse central plane of the spreader.

This invention relates to a load equalizer, useful in the handling of loads such as ships cargoes.

Heavy, bulky loads are ordinarily handled at pier-side by means of a single cargo hook (providing a single point of suspension) from which the load is suspended through separate couplings between the hook and the respective ends of the load. When the load is off balance, that is when its weight is distributed non-uniformly so that its center of gravity is displaced from the spatial center of the load, some form of adjusting or leveling apparatus must be utilized in order to maintain the load in a substantially level (horizontal) attitude when it is lifted. Such adjusting or leveling apparatus operates to in effect bring the (single) point of suspension into vertical alignment with the center of gravity or center of weight of the load. The adjusting or leveling apparatus referred to is particularly necessary when containerized loads of a standard size are to be stacked within closely-fitting guides in a socalled container ship. Such containers are ordinarily handled by the use of a spreader (which is a rectangular frame conforming in size to the upper face of the container and having latches which match lifting fittings provided at the upper corners of the container). The offbalance load, i.e., the unevenly distributed lading in the containers, is quite unpredictable.

Even if the containerized loads are balanced, it may be necessary to handle or stack them at an angle, e.g. when they are to be stacked within guides in a ship and the fore-and-aft trim of the ship is something less than perfect.

Previously, there have been developed so-called selfleveling spreaders, for handling off-balance containerized loads. These spreaders have the leveling apparatus mounted as fixed components on the spreader. With these devices, the container, with the attached spreader, must be manipulated in order to either extend or shorten-up the load to the desired level. The container, with the attached spreader, performs all of the gymnastics during this operation, and this action alone introduces higher resultant forces in the included angles between the spreader corners and the wire rope leads to the cargo hook; this in turn creates a higher bending moment in the spreader frame structure, which will ultimately lead to an item of maintenance.

Furthermore, the exotic self-leveling spreaders of the prior art are necessarily limited to use with containers, whereas it is often desired to handle unbalanced bulk loads without a spreader by means of a single cargo hook (these unbalanced situations would of course call for some form of leveling apparatus). The apparatus of the present invention, which is an independent and self-sustaining piece of equipment which may be suspended and operated in conjunction with an existing cargo hook and either with or without a conventional spreader (conventional here referring to one not having any self-leveling feature), may be termed a load equalizer.

An object of this invention is to provide novel load equalizing or leveling apparatus useful for the handling of ofi-balance loads by means of a cargo hook.

Another object is to provide apparatus which operates to easily convert any spreader into a self-leveling spreader.

A further object is to provide novel load equalizer apparatus.

The objects of this invention are accomplished, briefly, in the following manner: An elongated rectangular frame (comprising the main support for the load equalizer of the present invention) is suspended at its four corners from a cargo hook by means of lines of fixed length, and each of the four corners of the frame is coupled by means of a separate tackle means (a separate set of falls) to a respective corner of the load (which latter may be, by way of example, a rectangular spreader frame from which is suspended a container). Each of the tackle means may comprise a so-called luff tackle comprising fixed and movable blocks one of which is attached to the frame and the other of which is attached to the load. For load leveling or load equalizing, all four of the sets of falls are operated simultaneously (thereby to vary the lengths of the couplings between the frame and the load) by powered driving means carried by the frame, the arrangement being such that the paired sets of falls on the same side of the major center line of the rectangle are operated in opposite senses. The powered driving means is controllable to operate the sets of falls in the appropriate direction to in effect bring the center of gravity of the load equalizer frame into vertical alignment with the center of gravity or center of weight of the load (which latter may be container plus spreader).

Although the previous description has generally ref ferred to an off-balance load suspended at its end from a single point (when containerized, handled with a spreader, or when of other type, handled without a spreader), a similar leveling requirement arises in the case of elongated uniform loads suspended by means of two longitudinally-spaced slings, where the slings are not placed exactly symmetrically with respect to the load.

A detailed description of the invention follows, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a top plan view of the load equalizer frame the invention, together with the equipment carried therey;

FIG. 2 is a front elevation of the assembly shown in FIG. 1;

FIG. 3 is a somewhat schematic front elevation of the complete load equalizer apparatus, as set up to handle a load, this view illustrating two diiferent positions of the load equalizer apparatus; and

FIG. 4 is a side view of the apparatus shown in FIG. 3, with certain additional portions of the hoisting equipment.

In the ensuing description, similar elements are denoted by the same reference numerals but carrying prime designations.

Referring first to FIGS. 1 and 2, the load equalizer components are carried by a rigid frame denoted generally by numeral 1. Frame 1 is of rectangular configuration and is approximately four feet five inches wide by nine feet two inches long. Two channel members 2 and 2', each nine feet two inches long, form the longer sides of the rectangular frame 1. A pair of shorter channel members 3 and 4, each two feet four inches in length, are edge-welded to channel member 2 at the respective ends of the latter; a pair of similar channel members 3' and 4' are edge-welded to channel member 2 at the respective ends of member 2'. To form the shorter sides of the frame 1, as well as to provide additional support means for equipment to be later described, a pair of angle members and 6 are utilized at one end of the frame; member 5 extends transversely between members 3 and 3' and its ends are secured respectively to the outer end of member 3 and to the outer end of member 3'. Member 6 also extends transversely between members 3 and 3' and its ends are secured respectively to the inner end of member 3 and to the inner end of member 3. A pair of similar angle members 5 and 6 are utilized at the other end of the frame. Member 5' extends transversely between members 4 and 4 and its ends are secured respectively to the outer end of member 4 and to the outer end of member 4; member 6 also extends transversely between members 4 and 4' and its ends are secured respectively to the inner end of member 4 and to the inner end of member 4'.

A separate upstanding bracket plate 7 is mounted securely at each respective corner of frame 1, each such bracket plate being sandwiched between a respective one of the inner channel members and the adjacent ends of the angle members. Thus, referring to FIG. 1, at the lower left corner, a bracket 7 is sandwiched between channel member 3' and the adjacent ends of angle members 5 and 6; at the upper left corner, a bracket 7 is sandwiched between channel member 3 and the adjacent ends of angle members 5 and 6; at the upper right corner, a bracket 7 is sandwiched between channel member 4 and the adjacent ends of angle members 5' and 6'; at the lower right corner, a bracket 7 is sandwiched between channel member 4' and the adjacent ends of angle members 5' and 6'. A strengthening transversely-extend ing angle member 8 is secured between the upper portions of paired brackets 7 at the left-hand end of the frame, the ends of this angle member being welded to the inner faces of the respective brackets; similarly, at the right-hand end of the frame, a transversely-extending angle member 8' is secured between the upper portions of the other two brackets 7, the ends of angle member 8' being welded to the inner faces of the respective brackets. One edge 7a of each of the brackets 7 (see FIG. 2) extends upwardly and away from its respective corner of the frame, at an angle of about 47 with respect to the upper faces of the channels 2 and 2'.

An outstanding prismoidal mounting block 9 is utilized at each corner of the frame 1, the inner end face of each block being rigidly secured to the outer face of a respective bracket 7. The mounting blocks 9 are also secured along their respective side edges to the upper faces of the respective adjacent channel members 2, 2', 3, 3', 4, or 4'. Each of the mounting blocks 9 provides a mount for a respective lifting plate 10. The lower end face of each lifting plate 10 is secured as by welding to the upper portion of one of the side faces of a respective mounting block 9. Also, the inner face of each plate 10 is secured to the outer face of a respective bracket 7. Each of the lifting plates 10 has a pair of opposite faces which extend upwardly and away from the respective corner of the frame, parallel to the respective bracket edges 7a; a respective lifting aperture 11 is drilled through each of the plates 10 near the upper ends thereof, the center line of each aperture being at 90 to the pair of opposite faces just mentioned.

The four corner lifting plates 10 (which are rigidly secured to frame 1), and their respective apertures 11, provide an arrangement whereby the frame 1 may be suspended from a single point of suspension, such as a cargo hook. Four wire rope slings -12 of fixed length (say, about 4% feet) are utilized for the suspension, one sling for each of the four corners of the frame 1. One end of each of the slings 12 is provided with a bifurcated apertured shackle (not shown) which is designed to fit over a respective plate 10, with a pin passing through the apertures in the shackle and also through the respective lifting aperture 11 to secure the lower end of each of the four slings to a respective corner of the frame 1. The other end of each of the slings 12 has a loop formed therein, and the four slings are brought together over the center of the frame 1 and the looped ends thereof slipped over a cargo hook 13 (FIGS. 3 and 4), which serves as a single-point suspension for the load equalizer frame. Thus, the frame 1 is suspended from a single point by meanswhich extends to its four corners.

The cargo hook 13 may be a double cargo hook of the so-called rams-horn type (see FIG. 4). The cargo hook 13 forms a part of a ships cargo handling apparatus (cargo gear). For example, the hook 13 may be hung from the lower block 14 of a boom carbo falls 15 the upper block 16 of which may be hung from the head 17 of a cargo boom. The cargo boom, as is conventional, is mounted so that the boom head 17 may be moved through both horizontal and vertical arcs.

Two sheaves (grooved wheels) are rotatably mounted (for rotation independent of each other) at each of the four corners of the frame 1. Since all of the mounting arrangements for these sheaves are similar, only one will be described in detail, that at the lower left (front left) in FIG. 1.

A support bracket 18 is bifurcated at its upper end to surround the lower face of mounting block 9, at the outer end of the latter. A pin 19 passes through aligned apertures provided in the two prongs or tines of bracket 19 and in the outer end of block 9, to secure bracket 18 to block 9. The aforementioned aligned apertures extend parallel to the longer dimension of frame 1, and the bifurcation of bracket 18 may be said to be in this same direction. The lower end of bracket 18 is trifurcated or three-pronged in a direction parallel to the shorter dimension of frame 1. In the two inter-prong spaces provided between the three lower tines or prongs of bracket 18, an outer sheave 20 and an inner sheave 21 are respectively mounted. Sheaves 20 and 21 are mounted for free rotation about a pin 22 which passes in fixed (i.e., non-rotating) manner through aligned apertures provided in the three tines of bracket 18 and through clearance (or free-running) central holes in the sheaves 20 and 21. The usual apertured spacers may be provided on pin 22, between sheaves 20 and 21.

There are four pairs of sheaves 20 and 21, one pair at each of the four corners of the frame 1. Each pair of sheaves serves as the fixed double block for a respective set of falls (i.e., a variable-length coupling means, or a tackle means), there being four sets of falls in all; each set of falls comprises a so-called luff tackle and provides the equalizing feature of the load equalizer of the invention, as will be subsequently described.

The spatial configuration of the items 18-22 at each corner of the frame 1, with respect to the corresponding lifting plate 10 and aperture 11, is such that the center line of any one of the slings 12, if extended downwardly past its aperture 11, would pass approximately through the center of the corresponding pin 19 and then would intersect an outward extension of the center line of the corresponding pin 22. See FIGS. 1 and 2.

A twin wire rope drum 23, having two separate reeling sections 24 and 25 securely connected together to rotate as a single unit, is secured to a shaft 26 which is journaled for rotation on frame 1 by means of a pair of bearings 27 and 28; the axis of shaft 26 extends transversely to the longer dimension of frame 1 and is located at the center point of the longer sides of frame 1. Bearing 27 is a pillow block bearing which is secured to a plate welded to the top face of channel 2, centrally of the length thereof. Bearing 28 is also a pillow block bearing, and is secured to the outer end of an outrigger arrangement 29 welded at its rear side to the outer side face of channel 2' and extending outwardly from this channel and under the twin drum 23. Shaft 26 is coupled by means of a coupling to one of the two output shafts of a gear reducer unit 31 which has a double-extended output gear shaft. Gear reducer unit 31 is mounted in frame 1, approximately centrally thereof, by bolting the same to two mounting plates 32 and 33 welded at their ends to respective supporting plates 34 and extending transversely of the frame and in turn welded at their ends to the respective channels 2 and 2. The upper edges of the plates 34 and 35 are shown in FIG. 1, Unit 31 may be a single helical worm gear unit.

A similar twin wire rope drum 23', having two separate reeling sections 24 and 25, is mounted at the rear side of frame 1, in alignment with drum 23. The mounting and drive of the rear drum 23' are exactly similar to those of the front drum 23 previously described, with shaft 26', bearings 27' and 28', outrigger 29', and coupling 30 being exactly similar to the corresponding previouslydescribed elements with unprimed designations. Shaft 26 (which drives the twin drum 23, just as shaft 26 drives the twin drum 23) is coupled by means of coupling 30' to the other of the two output shafts of gear reducer unit 31. Shafts 26 and 26' are rotated in the same direction by unit 31, thus driving the two drums 23 and 23 in the same direction.

The drums 23 and 23' are located vertically with respect to sheaves 20 and 21 in such a way that the lowermost point on the circumferences of the reeling sections 24, 24, 25, and 25' is approximately in the same horizontal plane as the uppermost point on the circumferences of the various sheaves 20 and 21. Thus, again referring to FIG. 1, a wire rope 42 wound on reeling section 24' may pay out from the bottom of this section and pass over the top of outer sheave 20 at the upper left corner of frame 1; a wire rope 43 wound on reeling section 25 may pay out from bottom of this section and pass over the top of inner sheave 21 at the upper right corner of the frame; a wire rope 44 wound on reeling section 25 may pay out from the bottom of this section and pass over the top of inner sheave 21 at the lower right corner of the frame; a wire rope wound on reeling section 24 may pay out from the bottom of this section and pass over the top of outer sheave 20 at the lower left corner of the frame.

An electric motor 36 provides the motive power for drums 23 and 23', through the gear reducer unit 31. The frame of motor 36 is bolted to a pair of longitudinallyextending, spaced, parallel foundation plates 37 and 38 whose ends are firmly secured to the respective angle members 5 and 6 at the left-hand side of frame 1, the location of motor 36 being such that its output shaft 39 is centered along the'shorter side of frame 1. By way ofexample, the motor 36 may have a capacity of fifteen horsepower, at 900 r.p.m. A suitable coupling 40 connects together the motor output shaft 39 and the input shaft 41 of the gear reducer unit 31. The motor 36 is reversible; rotation of its output shaft 39 in one direction or the other, selectively, causes rotation of drums 23 and 23 in one direction or the other, selectively; as previously stated, the two drums 23 and 23' rotate in the same direction.

The wire ropes 42-45 provide the instrumentalities whereby lifting forces are transmitted from the load equalizer frame 1 to the load; they also comprise a part of the variable-length coupling means whereby the load equalizing function or the leveling action may be accomplished. Refer now to FIGS. 3 and 4. For purposes of illustration only, the load being handled may be considered to be a containerized load (the container itself not being shown in these figures) which is adapted to be attached to a forty-foot container spreader 46, and thus to be suspended therefrom. The container (which is typically the forty-foot size, which means about forty feet in length) is hexahedral, and the spreader frame 46 is of rectangular configuration, with its length and width conforming to those of the container. The spreader is not illustrated in detail herein, since it forms no part of the present invention. A spreader suitable for use with the load equalizer of this invention is described in the copending Griffith application, Serial No. 608,838, filed January 12, 1967. Sufiice it to say here that the container is adapted to be attached at its upper four corners by means of latches carried by the spreader to the respective corners of the spreader frame 46. It will be assumed that a container is attached to spreader frame 46, so that the off-balance load being handled by the load equalizer of this invention amounts to container plus spreader.

At each of the four upper corners of the spreader 46, there is provided a bar 47 welded to the spreader frame, each bar having a hole therein which receives the shackle pin of a respective anchor shackle 48 whose looped upper end is passed through a thimble provided on the lower end of a repective wire rope pendant 49 of fixed length. All four of the wire rope pendants 49 are of the same fixed length, which may be about 11 /2 feet. The upper end of each of the lower fixed length pendants 49 is provided with a thimble which receives the shackle pin of a respective anchor shackle 50 whose looped upper end is passed through a link 51 secured to a respective single pulley block 52 provided with a becket. There are four pulley blocks 52, one for each of the four corners of the spreader (or, more precisely, one for each of the four fixed-length pendants 49), and each pulley block 52 cooperates with one pair of sheaves 28-21 (as will be detailed hereinafter) to provide a set of falls for equalizing purposes. Thus, there are four sets of falls in all, one set for each of the four corners of the load. Each set of falls, as will be described, can act as a variablelength coupling means.

For the forty-foot spreader 46 illustrated, each pendant 49, together with its appurtenant attaching hardware, may be thought of as a separate load attachment means which is coupled to the load (spreader plus container) at one end and to the variable-length coupling means (falls) at the other end. For a twenty-foot container spreader (which would of course be used in conjunction with a twenty-foot container), the pendants 49 would not be used, and the links 51 would be attached directly to the respective anchor shackles 48 (which latter are attached directly to the spreader). In this latter or twenty-foot case, the anchor shackles 48 could be thought of as the load attachment means (since they would be coupled to the spreader-plus-container load and to the equalizing falls or variabledength couplings).

Considering first the two front corners of the equalizer frame 1, one end of the wire rope 45 is secured to the reeling section 24 of two drum 23 and, proceeding from this end, the wire rope is wound for several turns in one certain direction around the drum 23 (as illustrated) this direction is clockwise as viewed from the front in FIG. 1), then passes off the bottom of the drum, over the top of outer pulley 20 at the left-hand front corner of frame 1, then down and around the front left-hand pulley block 52 (see FIG. 3), then back up and over the top of inner pulley 21 at the left-hand front corner of frame 1, then back down to pulley block 52, where the other end of this length of wire rope 45 is secured to the becket of the front left-hand pulley block (movable block) 52.

One end of the wire rope 44 is secured to the reeling section 25 of twin drum 23 and, proceeding from this end, the wire rope is wound for several turns oppositely to the direction of winding of rope 45 on the drum 23 (as illustrated, the direction of winding of rope 44 on the drum is counterclockwise as viewed from the front in FIG. 1), then passes off the bottom of the drum, over the top of inner pulley 21 at the right-hand front corner of frame 1, then down and around the front right-hand pulley block 52, then back up and over the top of outer pulley 20 at the right-hand front corner of frame 1, then back down to pulley block 52, where the other end of 7 this length of wire rope 44 is secured to the becket of the front right-hand pulley block 52.

It may be seen that each of the two sets of falls just described in detail (one set being for the left-hand front corner of frame 1 and the other set being for the righthand front corner of the frame), that is, each of the two tackle means or two variable-length coupling means described, comprises a so-called luff tackle, with two fixed sheaves and 21 and one single movable block 52. Since the two reeling sections 24 and 25 of twin drum 23 have the same diameter and are rigidly secured together, and since the wire ropes 45 and 44 are wound oppositely on drum 23, it may be seen that, when this drum is rotated in one direction by motor (acting through gear reducer 31), cable 44 is unwound from the drum at the same rate that cable is wound onto this drum; when the drum 23 is rotated in the other direction, cable 45 is unwound from the drum at the same rate that cable 44 is wound onto this drum. Thus, when motor 36 is energized, the two variable-length coupling means (that is, the two sets of falls) at the front corners of frame 1 are varied in length equally but in opposite directions.

The winding or roving of the two falls at the back or rear corners of frame 1 is quite similar to that of the two falls at the front corners of the frame, it being noted that the wire rope 43 for the set of falls at the righthand rear corner is wound in the same direction around drum 23 (counterclockwise as viewed from the front in FIG. 1) as is wire rope 4, around drum 23, for the set of falls at the right-hand front corner; the wire rope 42 for the set of falls at the left-hand rear corner is wound in the same direction around drum 23 (clockwise as viewed from the front in FIG. 1) as is; wire rope 45,

around drum 23, for the set of falls at the left-hand front corner. Thus, when drums 23 and 23' are rotated in one direction by motor 36, cables 44 and 43 are both unwound from their respective drums at the same rate that cables 45 and 42 are wound onto their respective drums; when drums 23 and 23' are rotated in the other direction, cables 45 and 42 are both unwound from their respective drums at the same rate that cables 44 and 43 are wound onto their respective drums. Consequently, when motor 36 is energized, the two variable-length coupling means at the right-hand side (i.e., front and rear right-hand corners) of frame 1 are varied in length equally but oppositely to the two variable-length coupling means at the left-hand side (i.e., front and rear left-hand corners) of the frame.

The load equalizer of this invention is designed be capable of balancing-out loads of up to 80,000 pounds (cargo hook load) by physical determination, before and/ or during lifting of containers (loaded or unloaded), whether from pier, truck-trailer bed, deck, or ship-container-guide system, without undue tendency toward bending or racking. Moreover, the load equalizer is capable of tilting the spreader frame when preparing to enter or leave the ship-container-guide system, in cases where the ship is not on an even keel. This will become clearer from the following description of the operation of the invention.

Refer again to FIGS. 3 and 4. Assume that the load (container plus spreader) to be lifted off is in an extreme off-balance or unbalanced condition, wherein the center of weight of the load is located a distance of onethird of the container length from the let-hand end thereof; thus, the center of weight of the load is located on the vertical line 53 in FIG. 3. Assume also that the load equalizer is originally in a neutral or level position, wherein its center of gravity (center of gravity of the frame 1 plus the apparatus carried thereby) is located on the vertical line 54 in FIG. 3 (which line passes through the center of the length of spreader 46). In this neutral position, the four distances (one at each corner of the spreader) between the center of sheaves 20, 21 and the top of the spreader 46, measured in the slant-line directions of the pendants 49, are all equal. This common distance may be termed A (this reference character not being shown in the drawings, however). The distance in question might also be thought of as the distances between the center of sheaves 20, 21 and the center of the respective pulley blocks 52, since the pendants 49 are all equal in length and are fixed in length. For convenience, however, the greater distances (i.e., all the way down to the spreader 46) will be considered here. The load equalizer is so designed that, in its neutral position, there are 4 /2 turns of wire rope on each of the reeling sections 24, 25, 24', and 25.

The original condition (the first phase of the operation) is at tight-line only, the lines being those of the boom car o falls 15 and the four sets of load equalizer falls 20, 21, 52.

In the second phase of the operation for lift-off from a pier, trailer bed, or deck, the load is lifted approximately one degree (to determine the direction of the center of weight of the load with respect to the center of gravity of the load equalizer). In the case assumed, the center of weight of the load (on line 53) is to be left of the center of gravity of the load equalizer (on line 54), so that this one degree of lift would appear at the righthand end of the container. This end of the container may be termed the high end. During this initial small lift, the lower block 14 of the boom cargo falls 15 will tend to move in the direction of the center of weight of the container, so that in the assumed case it would tend to be pulled toward the left of longitudinal center line 54.

Next, the load is equalized preparatory to lift-off. This is done by lowering away of the two load equalizer falls at the high end of the container, thus modifying the lengths A previously referred to. Motor 36 is energized in the appropriate sense to drive drums 23 and 23' so that wire ropes 44 and 43 are unwound from their respective reeling sections 25 and 25', and wire ropes 45 and 42 are wound onto their respective reeling sections 24 and 24'. This lowers away the two load equalizer falls 20, 21, 52 at the high or right-hand end of the container, and raises up the two load equalizer falls 20, 21, 52 at the left-hand end of the container. The original A distances at the right-hand end of the container thus increase during this leveling or equalizing operation, and the original A distances at the left-hand end at the container decrease the same amount. The load equalizer frame 1 travels during this operation, as a result of the travel of the load equalizer falls. During the load equalizing operation, the cargo boom head 17 is ordinarily moved (by appropriate manipulation thereof) to suit the line of pull. It may be noted here that the load equalizer and the container each share the act of change in position.

At the end of the equalizing operation, the load is equalized and ready for lift-off. This marks the third phase of the overall operation. At the end of the load equalizing operation, the load equalizer has been moved to the position shown in dotted lines in FIG. 3, the two load equalizing falls at the right-hand end of the container having been lowered away (thus increasing the distance between sheaves 20, 21 and block 52 at this end) and the two load equalizing falls at the left-hand end of the container having been raised up (thus decreasing the distance between sheaves 20, 21 and block 52 at this end). The two original distances A at the right-hand end of the container have been increased by an amount X, and the two original distances A at the lefthand end of the container have been decreased by an amount X. The center of gravity of the load equalizer has been moved laterally to lie on the line 53, in alignment with the center of weight of the load; in the example given, the amount of this lateral movement is about 6% feet. The cargo hook 13 has been moved to its dotted-line position (on line 53, to suit the line of pull) by manipulation of boom head 17.

It should be apparent that, if the center of weight of the load is located to the right of neutra line 54, an equalizing action opposite to that previously described would be made to occur. The motor 36 would be energized in the opposite sense, to lower away the two load equalizing falls at the left-hand end of the container and to raise up the two load equalizing falls at the right-hand end of the container; this would cause the two distances A at the left-hand end of the container to increase and the two distances A at the right-hand end of the container to decrease, by the same amount.

It is pointed out that, in the present invention, the load equalizer is not located at the spreader (as in prior devices), but is located at the cargo hook. This is an ideal location for the equalizer, due to the fact that the hook is a floating component, and this, coupled with the ability of the load equalizer to walk over in the offbalance direction, minimizes the total required leveling motion.

A mode of operation analogous to, but slightly different from, that previously described is utilized when a container is lifted out of the container guide system of a so-called container ship. In this situation, for the second phase of the operation the load (container plus spreader) is lifted sufiiciently to cause the container to press hardup on one pair of end guides, to determine the direction of the center of weight of the load with respect to the neutral line or longitudinal center of the container. If the center of weight of the load is located to the left of neutral, the container when lifted would press against the left-hand pair of end guides; if the center of weight of the load is located to the right of neutral, the container when lifted would press against the righthand pair of end guides. Once the off-balance direction of the load is known, the load equalizer would be operated as before described to equalize the load preparatory to lift-out, but in this situation the equalizing falls on the end opposite to that against which the container presses are lowered away.

A spring-loaded cable reel 55 is mounted on frame 1 at the right-hand side thereof and centrally of the shorter dimension of the frame. Reel 55 is attached to the frame by means of bolts 56 which pass through aligned apertures provided in the base plate of the reel and in the angle members 5' and '6. This reel carries an electric cable one end 57 of which (see FIG. 3) extends to the boom head 17 and thence along the boom to the source of power for motor 36 and to the push 'button controls for this motor. Of course, certain conductors of this cable are connected, by means of wiring, panels, etc. mounted on the equalizer frame 1, to electric motor 36.

The load equalizer of this invention is actuated through the use of a hand-held three-push-button type of control box attached to a flexible walk-around cable (in turn suitably connected to the cable end 57, at the base of the cargo boom) of sufficient length to permit the operator to observe cargo operations on the pier as well as within cargo holds of the vessel. The first of these three push-buttons permits manual controlled movement of the load equalizer in one direction (by energization of motor 36 in one sense). The second push-button permits manual controlled movement of the load equalizer in the opposite direction (by energization of motor 36 in the opposite sense). The third push-button provides an automatic self-leveling action (responsive to a levelsensitive type of switch on spreader frame 46) which operates on a limited time basis (thus preventing undesired oscillation, back and forth, of the equalizer). This last push-button is utilized, in the main, for automatic finalized leveling of the load while in transit (during the loading or unloading cycle of the ships cargo). It is also utilized, after the load has been deposited in its position, for returning the unloaded (or light, with only the spreader) load equalizer back to its original neutra position, in preparation for approaching its next lift assignment.

In the event that a spreader such as is disclosed in the aforementioned application (which spreader may call for electrical control of its hydraulic actuating mechanisms) is being utilized, certain conductors 58 of the electric cable carried by reel 55 may extend downwardly from equalizer frame 1 to spreader frame 46. The reel 55, which as stated is spring-loaded, acts to maintain the cable portions 57 and 58 reasonably taut throughout the range of movements of the load equalizer falls 20, 21, 52 and of the boom cargo falls 15.

The load equalizer device of this invention provides numerous advantages. With this device, it is not necessary to purchase a complete, rather exotic self-leveling spreader; this device can convert any spreader into a selfleveling spreader. Moreover, it is not necessary to possess a load equalizer for each spreader; rather, one load equalizer for each heavy lift cargo hook per ship is suflicient.

A further potential for a shipowner/operator lies in that it is not necessary to ship-out the load equalizer with vessel departure. Rather, it may be kept pier-side. If this is done, several advantages result. First, it will be exposed to fresh air atmosphere only, thereby reducing maintenance. Next, the equalizer can be at the service and disposal of all container ships of an owners fleet which have a boom of sufficient handling capacity. Further, if the servicing of vessels other than container ships (such servicing, of course, involving lifting operations without a spreader) is desired by the owner, the load equalizer of the invention (with slight modification of cable lengths and affected machinery) can be used for: (1) all loading or unloading operations involving unbalanced bulk lifts up to 80,000 pounds of cargo hook load; (2) handling lengthy bulk loads (longer than hatch openings) in and out of lower hold spaces through the procedure of snaking in and out (the load equalizer in this case being used to tilt the load to a desired angle, without secondary means). Even with a spreader, when the load equalizer is retained pier-side it may be used for handling containers at pier-side prior to the arrival, and after the departure, of a vessel.

In regard to item (1) above, it has been stated hereinbefore that the load equalizer of the invention can used for handling elongated uniform loads suspended by means of two longitudinally-spaced slings. In this case, the four lower blocks 52 of the equalizer would be utilized to handle the load having a two-point suspension. This could be accomplished by attaching a shackle of each of the four pulley blocks 52 (e.g., through the respective links 51) and then, in turn, coupling the two shackles of each end pair of blocks to a respective third larger shackle. Each of the two larger shackles (one at each respective end of the equalizer) would then be attached directly to a correspending one of the two and slings on the load. Then, if the two end slings are not placed exactly symmetrically on the load (as is almost always the case), the load equalizer may be operated in the manner previously described, to level or equalize the load. (During the leveling, one of the larger shackles would move closer to the equalizer frame 1, and the other would move further away from this frame.)

In addition, the load equalizer of the invention may be utilized for handling fully loaded twenty-foot containers and partially loaded forty-foot containers, without the use of a spreader; this use of the equalizer is applicable to containers stowed on decks and on hatch covers. This use of the invention (for handling containers, without a spreader) would require the provision of fittings matching those of the container at the lower end of each of the four pendants 49, or on the links 51 (for the smaller-sized containers). In connection with the foregoing, it is noted that the load equalizer may also be used for handling emptly containers Without Spreaders provided, of course, that the fittings mentioned in the preceding sentence are employed). Occasionally, the

shipowner/operator may find that a large percentage of his empty containers have accumulated in foreign parts. Rather than burdening his own vessel with a dead-head run, it is possible, and may be desirable, to leaseout a load equalizer to, and make a contract with, some vessel making these a port of call, the contract calling for the return of stacked empties as gravy deck cargoes.

The invention claimed is:

1. In apparatus for handling a demountable body from a single point of suspension, a rectangular spreader adapted to be attached to said body at four points, two on each side of the body, a substantially rectangular 'frame suspended at its four corners from said point, a separate variable-length coupling means for coupling each of the four corners of said frame to a respective corner of said spreader, and controllable means for varying the lengths of all four of said coupling means simultaneously, said controllable means operating to vary the lengths of the two coupling means on the same side of the longitudinal central plane of said frame in opposite senses.

2. Apparatus in accordance with claim 1, wherein said rectangular frame is suspended from said point by means of four lines of fixed length each coupling said point to a respective one of the four corners of said frame.

3. Apparatus according to claim 1, wherein each of said variable-length coupling means comprises a fixed and a movable block associated together to form an operative set of falls, one of the blocks of each set of falls being attached to said frame at respective corners thereof and the other block of each set of falls being attached to said spreader at respective corners thereof.

4. In apparatus for handling a hexahedral container whose length is greater than its width from a single point of suspension, a rectangular spreader having a length and width conforming to those of the container and adapted to be attached at its four corners to the four upper corners of the container, a substantially rectangular frame suspended at its four corners from said point; first, sec- 0nd, third, and fourth variable-length coupling means for respectively coupling the four corners of said frame to the corresponding corners of said spreader; controllable means for (1) varying the lengths of the two coupling means on one side of the longitudinal central plane of said frame simultaneously and in opposite senses, and for (2) varying the lengths of the two coupling means on the other side of the longitudinal central plane of said frame simultaneously and in opposite senses.

5. Apparatus in accordance with claim 4, wherein said rectangular frame is suspended from said point by means of four lines of fixed length each coupling said point to a respective one of the four corners of said frame.

6. Apparatus in accordance with claim 4, wherein said controllable means operates to vary the lengths of the two coupling means on the same side of the transverse central plane of said frame in the same sense.

7. Apparatus according to claim 4, wherein each of said variable-length coupling means comprises a fixed and a movable block associated together to form an operative set of falls, one of the blocks of each set of falls being attached to said frame at respective corners thereof and the other block of each set of falls being attached to said spreader at respective corners thereof.

References Cited UNITED STATES PATENTS 2,020,306 11/1935 Fitch 294-67.4 3,191,983 6/1965 Gaglione 294--81 3,330,590 7/ 1967 Sheridan 29481 FOREIGN PATENTS 180,321 4/1966 Russia. 271,724 11/1950 Switzerland.

EVON C. BLUNK, Primm'y Examiner.

H. C. HORNSBY, Assistant Examiner. 

